It has the source code of many of your familiar favorites, like
mysql, which everybody has used to connect to the MySQL server
at one time or another. There are other utilities too in fact,
you'll find the source of most client-side programs here. There
are also programs for checking the password, and for testing
that basic functions such as threading or access via SSL are
possible.

You'll notice, by the way, that we're concentrating on the files
that have extension of ".c" or ".cc". By now it's obvious that C
is our principal language although there are some utilities
written in Perl as well.